Other Assets - Schedule of Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid manufacturing costs	$ 7,121	$ 7,646
Prepaid selling, general and administrative expenses	3,616	2,265
Prepaid research and development expenses	1,405	1,288
Total other current assets	$ 12,142	$ 11,199